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 <h1>范例</h1>

 <p class="para">
  <div class="example" id="example-3307">
   <p><strong>Example #1 Factorial function using GMP</strong></p>
   <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /></span><span style="color: #007700">function&nbsp;</span><span style="color: #0000BB">fact</span><span style="color: #007700">(</span><span style="color: #0000BB">$x</span><span style="color: #007700">)&nbsp;<br />{<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">$return&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;for&nbsp;(</span><span style="color: #0000BB">$i</span><span style="color: #007700">=</span><span style="color: #0000BB">2</span><span style="color: #007700">;&nbsp;</span><span style="color: #0000BB">$i&nbsp;</span><span style="color: #007700">&lt;=&nbsp;</span><span style="color: #0000BB">$x</span><span style="color: #007700">;&nbsp;</span><span style="color: #0000BB">$i</span><span style="color: #007700">++)&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">$return&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">gmp_mul</span><span style="color: #007700">(</span><span style="color: #0000BB">$return</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$i</span><span style="color: #007700">);<br />&nbsp;&nbsp;&nbsp;&nbsp;}<br />&nbsp;&nbsp;&nbsp;&nbsp;return&nbsp;</span><span style="color: #0000BB">$return</span><span style="color: #007700">;<br />}<br /><br />echo&nbsp;</span><span style="color: #0000BB">gmp_strval</span><span style="color: #007700">(</span><span style="color: #0000BB">fact</span><span style="color: #007700">(</span><span style="color: #0000BB">1000</span><span style="color: #007700">))&nbsp;.&nbsp;</span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?&gt;</span>
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</code></div>
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 <p class="para">
  This will calculate factorial of 1000 (pretty big number)
  very fast.
 </p>
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